Vertical transmission of Trypanosoma cruzi represents approximately 20% of new Chagas disease cases. Early detection and treatment for women of childbearing age and newborns is a public health priority, but the lack of a simple and reliable diagnostic test remains a major barrier. We aimed to evaluate the performance of a point-of-care loop-mediated isothermal amplification (LAMP) assay for the detection of Tcruzi. In this proof-of-concept study, we coupled a low-cost 3D printer repurposed for sample preparation and amplification (PrintrLab) to the Eiken Tcruzi-LAMP prototype to detect vertically transmitted Tcruzi, which we compared with standardised PCR and with the gold-standard algorithm (microscopy at birth and 2months and serological study several months later). We screened pregnant women from two hospitals in the Bolivian Gran Chaco province, and those who were seropositive for Tcruzi were offered the opportunity for their newborns to be enrolled in the study. Newborns were tested by microscopy, LAMP, and PCR at birth and 2months, and by serology at 8months. Between April 23and Nov 17, 2018, 986mothers were screened, among whom 276were seropositive for Tcruzi (28·0% prevalence, 95% CI 25·6-31·2). In total, 224infants born to 221seropositive mothers completed 8months of follow-up. Congenital transmission was detected in nine of the 224newborns (4·0% prevalence, 1·9-7·5) by direct microscopy observation, and 14more cases were diagnosed serologically (6·3%, 3·6-10·3), accounting for an overall vertical transmission rate of 10·3% (6·6-15·0; 23of 224). All microscopy-positive newborns were positive by PrintrLab-LAMP and by PCR, while these techniques respectively detected four and five extra positive cases among the remaining 215 microscopy-negative newborns. The PrintrLab-LAMP yielded a higher sensitivity than microscopy-based analysis. Considering the simpler use and expected lower cost of LAMP compared with PCR, our findings encourage its evaluation in a larger study over a wider geographical area. Inter-American Development Bank.